-LRB- CNN -RRB- -- The American Civil Liberties Union has called on officials in Massachusetts and Florida to conduct independent investigations into the shooting death of a man by an FBI agent .

Ibragim Todashev was fatally shot early May 22 during questioning about a 2011 triple homicide in Waltham , Massachusetts , as well as his relationship with deceased Boston Marathon bombing suspect Tamerlan Tsarnaev .

Law enforcement from Massachusetts and Florida as well as the FBI questioned Todashev at his Florida home .

Details about the circumstances of Todashev 's death have been few , and the gaps have been filled in by media reports quoting unnamed law enforcement sources .

The reports have raised the question about how much of a threat Todashev posed before being shot .

Father : ` Unarmed ' son ` not crazy ' enough to attack FBI agent who killed him

The FBI is conducting an investigation into the shooting , but the ACLU said that action is not enough .

`` Florida officials are simply deferring to the FBI , allowing the FBI to investigate itself , but it is difficult to accept the FBI 's honesty in this matter , '' Howard Simon , ACLU of Florida 's executive director , said in a statement Monday .

`` The FBI has offered completely incompatible explanations ; they have failed to explain how these inconsistent stories found their way into newspaper accounts of the shootings , and have not offered any clarifying comment about what really happened . ''

The rights group sent a letter to Massachusetts Attorney General Martha Coakley asking her office to investigate the role of officers from her state in the shooting . In Florida , the ACLU asked the Florida Department of Law Enforcement to investigate the role of Orlando police at the scene .

A U.S. government official briefed on the FBI investigation told CNN in May that Todashev had agreed to talk to authorities and noted he was never arrested or handcuffed .

Did missed connections in murder case open door to bombings ?

A samurai sword was in the room when Todashev sat down with two Massachusetts State Police detectives and a Boston-based FBI agent , but it was moved out of his reach , the U.S. official said .

After one of the detectives left the room , the other noticed Todashev was acting odd , and he texted that sense to the FBI agent with him -- the U.S. official told CNN . Those two law enforcement officials were the only ones with Todashev , according to this account .

Suddenly , Todashev knocked over a table -- knocking the FBI agent back into a wall -- and came at him with some sort of `` long-handled object '' that he 'd grabbed from behind him , according to the official .

The agent fired a few rounds , but Todashev kept on coming , the official said . He finally stopped after yet more gunshots .

A law enforcement official told CNN that Todashev attacked the FBI agent with a broom handle , not a sword .

Official : Dead Boston bombing suspect involved in 2011 slayings

@highlight

Ibragim Todashev questioned in May over links to one of the Boston bombing suspects

@highlight

Todashev was fatally shot by FBI agent during interrogation at his Florida house

@highlight

The ACLU wants independent investigations into Todashev 's death